Great-Grandmother is a skeletal demon figure within the hierarchy and Betty's grandmother. She actively intervenes in the human world to assess Danpei Kimogawa's suitability as Betty's husband. Her method involves deploying nubile nymphs to tempt Danpei during his cohabitation with Betty, creating interpersonal challenges designed to test his fidelity and commitment. This testing occurs concurrently with Betty's mission to defeat the demon Lutan.